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Expression and functional role of nitric oxide synthase in osteoblast‐like cells
Author(s) -
Riancho José A.,
Salas Eduardo,
Zarrabeitia María T.,
Olmos José M.,
Amado José A.,
FernándezLuna José L.,
GonzálezMacías Jesús
Publication year - 1995
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1002/jbmr.5650100315
Subject(s) - nitric oxide , nitric oxide synthase , citrulline , sodium nitroprusside , osteoblast , arginine , chemistry , lipopolysaccharide , cell culture , omega n methylarginine , microbiology and biotechnology , biochemistry , biology , endocrinology , in vitro , genetics , amino acid
Nitric oxide synthases (NOS) are enzymes that produce nitric oxide (NO) from L‐arginine in a reaction yielding citrulline as a coproduct. Nitric oxide modulates the activity of a wide variety of cells, but little is known about its effects on bone cells. In the present study we report that the NOS inhibitor N G ‐monomethyl‐L‐arginine (NMMA) induced a dose‐dependent inhibitory effect on the proliferation of the osteoblast‐like cell lines MG63 and ROS 17/2.8. The inhibitory effect was prevented by increasing L‐arginine concentrations in the medium and by the NO donor sodium nitroprusside. Likewise, NMMA inhibited interleukin‐6 secretion, independently of its effect on cell number. NOS expression by MG63 cells was confirmed by measuring their ability to metabolize radiolabeled L‐arginine to citrulline. NOS bioactivity was detected in unstimulated cells, but was markedly increased by stimulating the cells with cytokines, lipopolysaccharide, or 1,25‐dihydroxyvitamin D 3 . NOS activity was partially dependent upon the presence of calcium in the medium. Furthermore, constitutive‐type NOS (c‐NOS) and inducible‐type NOS (i‐NOS) mRNA expression was detected in ROS 17/2.8 cells after reverse transcription and polymerase chain reaction amplification. In conclusion, osteoblast‐like cells express c‐NOS and i‐NOS, and NOS activity seems to play an important role in the regulation of cell proliferation and function.